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Date: Fri, 12 Mar 2010 15:20:48 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [patch 05/10 -mm v3] oom: badness heuristic rewrite
Message-Id: <20100312152048.e7dc8135.kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <alpine.DEB.2.00.1003100239150.30013@chino.kir.corp.google.com>
References: <alpine.DEB.2.00.1003100236510.30013@chino.kir.corp.google.com>
	<alpine.DEB.2.00.1003100239150.30013@chino.kir.corp.google.com>
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Sender: owner-linux-mm@kvack.org
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Rik van Riel <riel@redhat.com>, Nick Piggin <npiggin@suse.de>, Balbir Singh <balbir@linux.vnet.ibm.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>

On Wed, 10 Mar 2010 02:41:32 -0800 (PST)
David Rientjes <rientjes@google.com> wrote:

>  	if (sysctl_panic_on_oom == 2)
>  		panic("out of memory(memcg). panic_on_oom is selected.\n");
> +
> +	limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT;

A small concern here.

+u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
+{
+       return res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+}

Because memory cgroup has 2 limit controls as "memory" and "memory+swap",
a user may set only "memory" limitation. (Especially on swapless system.)
Then, memcg->memsw limit can be infinite in some situation.

So, how about this ? (just an idea after breif thinking..)

u64 mem_cgroup_get_memsw_limit(struct mem_cgroup *memcg)
{
	u64 memlimit, memswlimit;

	memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
	memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
	if (memlimit + total_swap_pages > memswlimit)
		return memswlimit;
	return memlimit + total_swap_pages;
}

Thanks,
-Kame

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